Two-stroke combustion engine



April 16, 1929 o. KUHNAST 1,709,269

TWO-STROKE COMBUSTION ENGINE Filed Jan. 18, 1927 2 Sheets-Sheet l fly j.

April 16, 1929. Q KU HN AST 1,709,269

TWO-STROKE COMBUSTION ENGINE Filed Jan. 18, 1927' 2 Sheets-Sheet 2 Patented Apr. 16, 1929.

UNirED STAT-Es A 1,769,269 PATENT OFFICE.

OSWAID XUHNAST, O HORN, NEAR ROERMOND, NETHERLANDS.

Two-srnonn comBUsTroN ENGINE.

Application led January 18, 1927, Serial No. 161,904, and'in the Netherlands November 30, 1928*.y

The invention relates to a two-stroke cmbustion engine in which the part of the cylinder below the pistonserves as pumping room for the fuel-air-mixture, andior thispurpose is provided withV inlet 'portscontollable by the pistongandw connected with the Carburettor pipin andwith` exhaust. ports also controll?. le by the piston and connectedv the inlet ports of the working cylinderfhamvdelig) are arranged in the cylin- Moreov'er in the wall of the pumping room automatle Vsuction valves are arranged by which air may be aspired from the crank chamber. The invention consists further in providing a fan for the piping to the car'- burettor to support .the air supply.

The purpose of this invention is to obtain an etiicient atmnizationef the f ueland further such amovement of the supplied air and of the fuel-air-mixture that first a suiicient quantity of air for scavenging enters into the working cylinder and then the fuel-air-mixture and these quantities are kept separated as Y much as possible. In this way an 'eiiicient combustion is obtained and no fuel or at any.

rate as small a quantity as possible of--fuel is lost by scavenging. Y 'y One embodiment of the invention consists 'in forming a fan from by blades arranged at the periphery of the ily wheel and by a casing surrounding the same which at one side is provided with an inlet opening and at'the other side is connected with the carburettor.

In the drawing the invention is explained as follows:

Fig. 1 is a back view, partly in section, and

Fig. 2 is a side-view, partly in longitudinal section of an engine according to the invention.

In each of the-cylinders 1 a piston 2 is found which'by means 'of a piston rod 3 and a driving rod 4 is connected with the crank shaft 5.

` The cylinder is provided with inlet scavl engingports 6 and exhaust ports 7, as often A inlet scavenging usual with two-stroke cycle engines, these ports having a height of a part of the-piston stroke and whichin the lowest position vide Fig. 1) of the piston are fully open. The ports 6 are continuously connected with the space 10 below the piston by achann'el 8 and an opening 9 in the cylinder wall. This connection is secured at the lowest position of the piston by an opening 11in theV piston wall. Y j

' The space 10`which at its upper side is limited by the piston 2 is closed at its bottom by a wall 12 in which also a stuihng box 13 for the piston rod 3 is arranged.' Moreover valves 14 are disposed 1n this wall, which valves in the-illustrated embodiment consists of ball-s which are pressed t0 their vseat by one or more springs and then close the openings in-the wall 12. "l'f'oiasover Yports 15 havi/ngra; trapezoidal der wall which ports at the highest position of the piston connect the space below it with a channel 16 leading to the Carburettor 18. v

The fly wheel 19 being provided at its perlphery with a ring having blades 21 and rotating in the casing 20, by which the air isv drawn in through the opening 22 and is led through the piping 23 to the Carburettor 18 and further to the space 10 below the piston 2.

As soon as this depression is suiiicient the valves 14 will be lifted and air will be aspired from the crank chamber into the space 10.

In order to prevent the aspiration of lubricating oil splashing about in the crank chamber, below the valves 14, a screen 17 is 'arranged around the piston rod 3.

As soon as the inlet port 15 is left free-by the piston the space 10 becomes connected with the channel 116 and through this with the carburettor so that a ful-air-mixture will be aspired into the space 10 in which a relatively small depression in pressure prevails. valves 14 will then close and furthermore this space will be filled owing to the fan function of the fly wheel and the air which has come through the valve 14 into the space 10 will be pressedinto the channel 8'4 by the'entering air. A relatively small depression in pressure prevailing in the space 10 and in the channel 8 the air will not be mixed so much with the entering air-fuel-mixture but the latter will ress the air out. The channel 8 will then e filled with air. Furthermore it may be observed that the trapezoidal shape of the port 15 serves for removing the unfavourable influence of the sudden connection of the Carburettor with the space 10. After the piston has obtained its highest position, it is again lowered by which the fuel- The ' air-mixture in the space 10 and the channel 8 pumping space through which into this spac is compressed until the ports 6 are again opened and the mixture iiows into the combustion space.

As the air present in the channel 8 first enters into the cylinder` it is practically impossible that any fuel will be lost through the exhaust ports 7 on the other hand a complete filling is secured by the working of the a' cylinder, a piston in said cylinder, a bottom wall in said cylinder to serve as pumping and pre-compression space for the fuel-air-lnixture and scavenging air, said cylinder part being provided with trapeze-shaped inlet portsscontrollable. by the piston and connected with the Carburettor, and With exhaust ports also controllable by the piston, inlet port-s for the Working cylinder, automatic valves arranged in said bottom Wall of the air is aspired to scavenge the cylinder, a car burettor, an air supply piping connected t1 the Carburettor, an air fan in said piping whereby more eicientatomization'of the fue is obtained and a high pressure is imparted t' the scavenging air, and thereby neutralizing completely the vacuum in the space under th piston, preventing the uel-ai'rfmiXture ioW ing back in Case the piston drops and bring ing about a complete admission.

2. A two-stroke combustion engine accord ing to claim '1, wherein the fan consists of 1 bladed ring surrounding the periphery of th fly Wheel and a casing surrounding the same said casing at one side being provided with suction opening and at the other side bein; connected by means ola piping with the ear burettor. l

In testimony whereof I aiix my signature OSWALD KUHNAST. .l 

